Conventionally, as disclosed in, e.g., Patent Literature 1, a torque calibration of a dynamometer such as an engine dynamo or a chassis dynamo is carried out by fixing a calibration arm to a torque measurement rotor such as, e.g., a rotating drum or a rotating shaft of a dynamometer.
This fixation of the calibration arm is manually performed by a user. More specifically, the user lifts the calibration arm to a predetermined position of the torque measurement rotor to be maintained still and then the calibration arm is bolted in this state to be fixed to the torque measurement rotor.
However, the calibration arm may be large in size and weight in some cases and, therefore, a plurality of workers are required to perform the fixation work and there is also required a fixing instrument in addition. Thus, the fixation work becomes a heavy and big work. There is also a problem that the fixation work is troublesome and it takes a long time to do the work. In addition, there is also a fear of dropping or falling of the calibration arm, and there is a problem in terms of safety.
After the calibration arm is fixed to the torque measurement rotor, the calibration is performed by suspending or placing calibration weights on the calibration arm one by one.
In the calibration work, the calibration weights are manually suspended or placed on the calibration arm by a user. Each of the calibration weights is heavy (as much as, e.g., 20 kg) and the work of placing the calibration weights on the calibration arm is a heavy work and there is a difficulty in terms of safety and workability.
In view of these problems as mentioned above, in order to reduce the work of suspending or placing the calibration weights on the calibration arm, there is suggested an automatic mounting device for automatically mounting calibration weights on a calibration arm, as disclosed in Patent Literature 2.
However, even in the case of using this automatic mounting device, the work of fixing the calibration arm to a torque measurement rotor is manually performed by a user, and it is further necessary to move the automatic mounting device near the calibration arm. In addition, when each of the calibration weights is placed on the calibration arm, it is necessary for the user to operate the automatic mounting device, and therefore the user is inevitably attending to the automatic mounting device all the time during the calibration.
Even though there can be reduce a burden of suspending or placing work of the calibration weights, the torque calibration is still accompanied by a manual work of fixing the calibration arm and, therefore, there is a difficulty in terms of safety and workability. Also, there is a problem that it takes a long time in an operation from the fixation of the calibration arm to an end of the torque calibration. Further, since it is necessary to operate the automatic mounting device during the torque calibration, there is a problem that the user subjects to constraints in time during the torque calibration.